1. Field of the Invention
The invention relates to an apparatus for positioning an optical element in a structure, the optical element being connected to the structure via fastening elements, and it being possible to set the position of the optical element by means of adjusting elements. The invention relates, in particular, to a projection objective for microlithography, a beam splitter cube being provided as optical element.
2. Description of the Related Art
Manufacturing and assembly tolerances that lead to aberrations in the objective inevitably occur during the assembly of optical imaging apparatuses, for example a projection objective for microlithography. It is known for the purpose of compensating these tolerances to reposition one or more optical elements appropriately in the objective. The same also holds for optical elements that need to be adjusted very exactly in the beam path.
It is known from DE 199 01 295 A1, for example, to displace one or more optical elements relative to the optical axis in order to compensate manufacturing and assembly tolerances and to correct aberrations.
WO 99/66361 discloses a positioning device for a lens, three degrees of freedom being present for positioning the lens.